1. Field of the Invention
This invention relates to feeder assemblies for delivering bar stock for processing by a machine tool and, more particularly, to a method and apparatus for removing unprocessed bar stock from the feeder assembly.
2. Background Art
It is known to process bar stock using different types of machine tools. In a typical system, a feeder assembly is utilized through which bar stock is delivered stepwise to a processing station at which any of a number of different operations can be performed thereon. As but one example, the bar stock is advanced to expose an end portion which is processed and cut from the remaining portion of the bar. The remaining portion of the bar is then advanced to repeat the same and/or a different processing step. This procedure is carried on repetitively until the bar length is reduced to a point that the remaining portion cannot be converted by processing into a usable form.
In one such system, the feeder assembly has a through passageway which is coaxial with the axis of a rotary spindle chuck. The bar stock is incrementally advanced and gripped by the chuck, whereupon the spindle is rotated to facilitate processing of the exposed bar stock material.
There are basically two different ways to advance the bar stock through the spindle. One technique involves pulling the bar stock from the downstream processing end. In one such system, a turret, which carries processing tools, also carries a puller which releasably grips the exposed leading/downstream end of the bar stock and draws it in an advancing direction sufficiently that it can be gripped to perform a processing operation thereon. Alternatively, the bar stock is pushed from a trailing/upstream end thereof to effect incremental advancement thereof through the spindle.
In many processing operations, the barstock is not matched to have a length that is an even multiple of the processed work piece length. As a result, there will remain an unusable piece of bar stock which must be removed from the feeder assembly before another longer piece of bar stock can be substituted therefor, advanced, and processed. If the unusable piece is of a sufficient length, a puller, such as that on the aforementioned turret adjacent to the processing location, can be used to separate the bar piece from the feeder assembly. Generally, this method is not preferred in that the unusable bar piece may not be conveniently removable from the feeder assembly at the processing location. Removal in this manner may cause interference with succeeding operations using the same processing equipment or with operations performed by other adjacent processing equipment.
The more preferable method of removing the unusable bar stock is to withdraw the same from the upstream end of the feeder assembly. To do so requires that the unusable piece of bar stock be grippable from the upstream end of a feeder tube and within the feeder tube by a pulling mechanism. In one conventional construction, a retrieval assembly has a gripper element that surrounds the upstream end of the bar stock so that the gripper element projects radially beyond the outer surface of the bar stock. The gripper element travel in a downstream direction within the feeder tube may be limited by any restriction therein, such as at a bearing, a restriction in a collet chuck, or the like. The restriction may be axially located so that it prevents the gripper element from engaging a portion of a piece of bar stock of sufficient length in a manner so as to allow another usable workpiece to be processed. As a result, an otherwise usable piece of bar stock is rendered scrap by the system limitations. An accumulation of unusable bar pieces, aside from causing inconvenience, may represent a significant financial loss, not only from the standpoint of material waste, but also by reason of requiring more frequent bar stock replacement, which interferes with ongoing processing efficiency.
In one form, the invention is directed to a method of processing a piece of bar stock material having spaced ends and a predetermined diameter. The method includes the steps of: attaching an adaptor to one end of the piece of bar stock material; directing the piece of bar stock material into a feeder sleeve bounding an internal passageway; moving the piece of bar stock material in the internal passageway from an upstream end of the internal passageway towards a downstream end of the internal passageway so as to expose a part of the piece of bar stock material for processing; performing at least one processing step on the exposed part of the piece of bar stock material; engaging a retrieval assembly with the adaptor; extending at least a part of the retrieval assembly into the internal passageway so that the at least part of the retrieval assembly does not project radially beyond the predetermined diameter from a downstream end of the at least part of the retrieval assembly to a predetermined distance in an upstream direction; and with the retrieval assembly engaged with the adaptor, repositioning the retrieval assembly to thereby reposition the piece of bar stock material within the internal passageway.
The adaptor may be attached to the piece of bar stock material before the piece of bar stock material is directed into the internal passageway. Alternatively, the adaptor may be attached to the piece of bar stock material with the piece of bar stock material extended at least partially into the internal passageway.
The adaptor may be attached to the one end of the piece of bar stock material in a number of different manners. As examples, the bar stock material may be attached by a spin welding process, by the use of a magnet, by a press-fit operation, through threaded engagement, etc.
The retrieval assembly may be engaged with the adaptor by a press-fitting operation.
In one form, the retrieval assembly has a first shoulder facing in a first direction, with the adaptor having a second shoulder facing oppositely to the first direction with the retrieval assembly engaged with the adaptor. The first and second shoulders abut each other so that the first shoulder acts against the second shoulder to cause the adaptor to follow movement of the retrieval assembly as the retrieval assembly repositions the piece of bar stock material.
At least one of the adaptor and retrieval assembly may be deformable to allow the first and second shoulders to be moved past each other and placed in facing relationship.
The method may further include the step of removing part of the piece of bar stock material during the performance of the at least one processing step so that a reduced size piece of the bar stock material resides at least partially in the internal passageway.
The method may include the step of removing the reduced size piece of the bar stock material from the internal passageway through the retrieval assembly.
The method may further include the step of separating the adaptor from the reduced size piece of bar stock material after the reduced size piece of bar stock material is removed from the internal passageway.
The adaptor that is separated from the reduced size piece of bar stock material may be attached to another piece of bar stock material.
The invention is also directed to a method of processing a piece of bar stock material having spaced ends between which an axis extends and a peripheral surface with a first effective diameter around the axis. The method includes the steps of: engaging a retrieval assembly with one end of the piece of bar stock material so that at least a part of the retrieval assembly has another, second, effective diameter that is not greater than the first effective diameter so that the piece of bar stock material will follow movement of the retrieval assembly in at least one direction along the axis; directing the piece of bar stock material into a feeder sleeve bounding the internal passageway; moving the piece of bar stock material in the internal passageway so as to expose a part of the piece of bar stock material for processing; performing at least one processing step on the exposed part of the piece of bar stock material; and with the retrieval assembly engaged with the piece of bar stock material, moving the retrieval assembly along the axis within the internal passageway and thereby moving the piece of bar stock material within the internal passageway.
The step of moving the piece of bar stock material may involve moving the piece of bar stock material from a position wherein the piece of bar stock material resides at least partially within the hollow passageway to a position wherein the piece of bar stock material is fully removed from the hollow passageway.
The step of engaging a retrieval assembly may involve attaching an adaptor to the one end of the piece of bar stock material and engaging the retrieval assembly with the adaptor. Alternatively, the retrieval assembly may be engaged directly with the piece of bar stock material.
The invention is also directed to the combination of: a piece of bar stock material having spaced ends between which an axis extends and a peripheral surface with a first effective diameter around the axis; an adaptor for attachment to one of the spaced ends of the piece of bar stock material with the adaptor in an operative position, wherein the adaptor does not project from the axis to beyond the first effective diameter of the peripheral surface; and a retrieval assembly engageable with the adaptor and which is repositionable to move the adaptor along the axis.
The retrieval assembly may be releasably attachable to the adaptor.
The combination may further include a feeder assembly including a sleeve with an internal passageway with a central axis and an effective diameter sufficiently large to receive the piece of bar stock material and least a part of the retrieval assembly.
The adaptor may be an element that is separate from and attached to the piece of bar stock material.
The invention is further directed to the combination of: a piece of bar stock material having spaced ends between which an axis extends and a peripheral surface with a first effective diameter around the axis; a retrieval assembly engageable with the piece of bar stock material so that the at least part of the retrieval assembly does not project radially beyond the first predetermined diameter from a downstream end of the at least part of the retrieval assembly to a predetermined distance in an upstream direction; and a feeder assembly having a sleeve with an internal passageway with a central axis and an effective diameter sufficiently large to receive the piece of bar stock material and at least part of the retrieval assembly.